Instructions
Load the "Call of Duty: Modern Warfare 2" game disc on your console and turn on two controllers. Press the center button on the controller to sign each controller into the desired profiles.
Select "Multiplayer" or "Spec Ops" from the main menu of the game and then press the button indicated onscreen to enable the second controller.
Select your mission (in Spec Ops) or match type (in Multiplayer) and then press "Start Game" (in Spec Ops) or "Join Match" (in Multiplayer). The game will now load with dual perspective enabled.